Slow Wave Sleep (SWS)

Last Updated: January 27, 2019

Definition - What does Slow Wave Sleep (SWS) mean?

Slow wave sleep (SWS) is the deepest of the three stages of non-rapid-eye-movement (NREM) sleep. NREM sleep accounts for 75-80% of the average person's total sleep time. The three NREM stages are collective referred to as "N1, N2 and N3" or "NREM1, NREM2 and NREM3." During the slow wave sleep stage of the sleeping cycle, an individual's consciousness and cortical activity are very low. This third level of slow wave sleep may also be referred to as delta-wave, or deep sleep.

WorkplaceTesting explains Slow Wave Sleep (SWS)

As a person progresses through the sleep cycle, he or she experiences both non-rapid-eye-movement (NREM) and rapid-eye-movement (REM) sleep. The different stages of sleep are determined by measuring the person's brain wave activity. among other methods. The majority of any sleeping period is spent in NREM sleep. While REM sleep is characterized by heighten brain activity,

NREM sleep is a period of increasing slowing brain activity as the body progresses from stage one to stage three. Stage three, slow wave sleep is characterized by delta brain wave activity. During slow wave sleep (SWS), a person sleeps deeply and is usually unaware of external stimuli. Breathing and heart rates are at their lowest during slow-wave sleep. Dreaming may take place during SWS, but not as often as during REM sleep. Behaviors known as parasomnias, such as sleep-walking or night terrors may occur during the SWS stage of the sleep cycle. Because SWS is such a deep sleep, a person who awakes during the slow wave stage of the sleep cycle may need up to thirty minutes to become fully awake and mentally alert.

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